In the 1950s and 1960s two tunnels were constructed next to a former chemical processing plant, the Plutonium Uranium Extraction Plant, or PUREX, located in an industrial area near the center of the Hanford Site called the 200 East Area. The tunnels were constructed of wood and concrete and covered with approximately 8 feet of soil. The tunnels were constructed to hold rail cars that were loaded with contaminated equipment and moved into the tunnels during the Cold War.

During a routine surveillance of the area this morning, a 20-foot-wide hole in the roof of one of the tunnels was observed, leading to the precautionary sheltering of employees and notifications to area counties and states. After no contamination was detected, the shelter in place order was lifted and employees were sent home from work early as a precaution. Workers continue to monitor the area for contamination as a crew prepares to fill the hole with clean soil.

The approximately 360-foot-long tunnel where the partial collapse occurred contains 8 rail cars loaded with contaminated equipment. That tunnel feeds into a longer tunnel that extends hundreds more feet and contains 28 rail cars loaded with contaminated equipment. The hole opened up in the shorter tunnel near where it joins the longer tunnel. The tunnels were sealed in the mid-1990s and are checked periodically.

And now one of them has collapsed…

This video, taken late on May 9, shows personnel laying down a gravel road that leads to the tunnel’s collapsed section. The road will provide a secure and clear path for workers to fill the tunnel opening.